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Home , Syngnathiformes

, a new (: ) from the Seychelles

John E. Randall1 and Sara A. Lourie2

1Bishop Museum, 1525 Bernice St., Honolulu, HI 96817-2704, USA 2Redpath Museum, McGill University, 859 Sherbrooke West, Montréal, Québec, H3A 2K6, Canada

Received July 29; accepted September 17, 2008

Abstract. Hippocampus tyro is described as a new species of seahorse from one specimen, 34 mm high and 61 mm in total length, dredged from 43–48 m off Poivre Atoll, Seychelles in 1992. It is unique for the genus in having 14 trunk rings and a single middorsal gill opening. It is compared with two other diminutive species, H. pusillus Fricke and H. jugumus Kuiter, sharing with them a slender body, confluent middorsal shoulder ridges, and similar spination.

Keywords: Syngnathidae, Hippocampus, new species, Seychelles

the specimen is a syngnathid. Regrettably, the tissue INTRODUCTION samples taken from the specimen resulted in the loss of the viscera, the anal fin, and most of the muscle of the The first author was fortunate to be a participant in a proximal half of the tail. marine biological expedition to the Seychelles aboard A large collection of was made during a the Dutch research vessel Tyro in 1992 (van der Land recent expedition to the Seychelles by the South African 1994). Fishes were collected in offshore stations by Institute for Aquatic Biodiversity. We have checked with trawls and dredges, and inshore with the use of the this institution for possible additional material of this ichthyocide rotenone, the anaesthetic quinaldine seahorse. Unfortunately, no specimens of Hippocampus sulphate, and by spearing. The expedition resulted in were collected, so we describe the species here from the the collection of 374 species of fishes, of which 108 were single specimen. new records for the Seychelles (Randall & van Egmond Proportional measurements, rounded to the nearest 1994). 0.05, are related to the head length (HL), measured Station 766 was a haul by a rectangular dredge on the from the tip of the snout to the most posterior edge of north side of Poivre Atoll in the Amirantes at a depth the shoulder ridge, or the total length (TL), determined of 43–48 m. A single small specimen of a seahorse was by bending a slender wire to the shape of the specimen, among the fragments of the corals Stylophora pistillata, straightening the wire, and measuring its length. Total Montipora digitata and Dendrophyllia sp. taken in the length is equivalent to standard length as defined by haul. A colour photograph was taken (Fig. 1), and the Lourie et al. (1999). Trunk length was measured by specimen was deposited in the Bishop Museum in bending a wire from the anterior edge of the first trunk Honolulu (BPBM) as Hippocampus sp. ring along the lateral trunk ridge to the anterior edge of When the specimen could not be identified to the first tail ring. The first trunk ring is the one bearing species in the review of by Lourie et al. (1999), the pectoral-fin base, and the last trunk ring, much it was sent on loan to the second author. Although it deeper than the first tail ring, contains the anus. The keys to the genus Hippocampus in Dawson (1985) and measurements of maximum depth of the trunk and tail Dawson in Smith and Heemstra (1986) by having a were made from the outer edge of the superior median prehensile tail and the head angled ventrally by more trunk or tail ridge to the median ventral or tail ridge than 70°, its slender body form and the high number of trunk and tail rings suggested a relationship to the Hippocampus tyro sp. nov. pipehorse genus . After initial attempts at Figs. 1–2 DNA sequencing by the second author, the specimen was sent to a colleague who was willing to try using Holotype. BPBM 35555, female, 61 mm TL, Seychelles, a different protocol, in spite of the initial preservation Amirantes, north end of Poivre Atoll, 5°44’S, 53°20’E, in formalin. The tissue yielded only a conclusion that coarse calcareous sand and coral, 43–48 m, rectangular

Smithiana Bulletin 10: 19-21 20 Randall & Lourie New Hippocampus species from the Seychelles 21 dredge, R/V Tyro Station 766, J. van der Land et al., 29 ridge; colour in preservative uniform greyish white; spine; a transverse pair of blunt spines ventrally on head depth, 38 vs. 34 tail rings, and 14 or 15 instead of December 1992. colour when fresh light brown with whitish blotches, head slightly posterior to suborbital spine; coronet well- 12 or 13 pectoral rays. H. jugumus differs in having 12 grading to light orangish brown posteriorly on tail, and developed, its height 9.4 in HL; coronet oval and cup- trunk rings, 37 tail rings, 20 dorsal rays, a prominent to whitish ventrally on head and trunk; trunk and tail like in dorsal view, with a rugose spine projecting to branching supraorbital spine, and a longer snout. ridge spines white; filaments on spines dark brown. each side, followed by a narrow median ridge; anterior edges of cup descending and converging to a low,

arrow-like, median spine; 2 small spines in a vertical ACKNOWLEDGMENTS Description. Dorsal rays 15; pectoral rays 14 (15 on row ventral to coronet and above level of upper edge of right side); trunk rings 14; tail rings 38; subdorsal rings orbit; shoulder (cleithral) ridge continuous middorsally, 3; superior trunk ridge ending under with 2 We thank Dr Kate A. Moots of the University of Guam followed by a prominent, crest-like, median ridge; gill for her very thorough review of our manuscript. enlarged subdorsal spines that angle posterolaterally; opening a narrow middorsal slit in neck ridge between superior tail ridge commencing with 2 small subdorsal median posterior ridge of coronet and collar of shoulder spines in alignment with larger subdorsal spines ridge; a large, truncate, rugose spine on shoulder ridge LITERATURE CITED above; lateral trunk ridge continuous with inferior tail anterior to ventral third of pectoral-fin base; cheek spine ridge; spines of trunk and tail ridges moderate in size on shoulder ridge ventrally on head nearly half way Dawson, C. E. 1985. Indo–Pacific . Gulf Coast and blunt; first 8 dorsal trunk spines as double spines; to large V-shaped midventral head spine; a prominent third and seventh superior trunk spines and fourth, Research Laboratory, Ocean Springs, Mississippi. midventral spine on first trunk ring; ventral trunk keel 230 pp. eighth, and eleventh superior tail spines enlarged nearly as deep as pupil diameter; longest dorsal ray 3.1 (counts of tail spines include anterior 2 subdorsal Fricke, R. 2004. Review of the pipefishes and seahorses in HL; longest pectoral ray 4.2 in HL. Colour in alcohol (Teleostei: Syngnathidae) of New Caledonia, with spines); a slender, leaf-like, branching filament up to uniform greyish white, only the very small filament on an eye diameter in length on enlarged superior trunk descriptions of five new species. Stuttgarter Beiträge enlarged superior and tail ridges brown. Colour when zur Naturkunde Ser. A, no. 668: 1–66. and tail spines; superior trunk spines anterior to dorsal fresh as in Fig. 1. fin linked across back by a low double ridge; spines of Kuiter, R. H. 2001. Revision of the Australian seahorses superior tail ridge progressively smaller posteriorly, of the genus Hippocampus (: disappearing posterior to 26th tail ring; spines of inferior Etymology. This little seahorse is named for the Dutch Syngnathidae) with descriptions of nine new species. tail ridge not detected posterior to 12th tail ring; body R/V Tyro, in recognition of the vessel serving as the Records of the Australain Museum 53: 293–340. slender, the maximum trunk depth (seventh trunk ring, base for a very successful marine biological expedition Lourie, S. A., A. C. J. Vincent & H. J. Hall. 1999. between spines) 11.2 in TL; depth of tail at third tail ring to the Seychelles. Seahorses: an Identification Guide to the World’s Species 25.5 in TL; trunk length 3.2 in TL; head at right angle and their Conservation. Project Seahorse, London. x to trunk as photographed (80° in preserved specimen); Remarks. Hippocampus tyro is unique among known + 211 pp. head length 6.2 in TL; head depth from just posterior species of seahorses in having 14 trunk rings (8–13 Randall, J. E. & J. van Egmond. 1994. Marine fishes to coronet (hence at gill opening) to base of cheek in other species) and a single, slit-like, middorsal gill from the Seychelles: 108 new records. Zoologische spine (as defined by Lourie et al., 1999: fig. 4) 1.65 in opening. It is most similar to H. pusillus Fricke 2004, Verhoudelingen Leiden, no. 297: 43–83. HL; snout length 2.2 in HL; minimum snout depth 7.5 described from three specimens, 28.3–39.0 mm in Smith, M. M. & P. C. Heemstra (eds.). 1986. Smiths’ Sea in HL; maximum snout depth 4.5 in HL: eye diameter height, collected from 35–228 m off New Caledonia Fishes. Macmillan South Africa, Johannesburg. xx and the Loyalty Islands; and to H. jugumus Kuiter, 2001 + 1047 pp. known from one specimen, 44 mm in height, from Lord van der Land, J. (ed.). 1994. Oceanic Reefs of the Seychelles. Fig. 1. Holotype of Hippocampus tyro, BPBM 35555, Howe Island. H. tyro shares with both a slender body, Report on a Cruise of RV Tyro to the Seychelles in 1992 61 mm total length, Poivre Atoll, Amirantes, confluent shoulder ridges, and similar (though blunter) and 1993. National Museum of Natural History, Seychelles. spination. It differs from H. pusillus in the much greater Leiden. 192 pp.

Diagnosis. Dorsal rays 15; pectoral rays 14 or 15; trunk rings 14; tail rings 38; subdorsal rings 3; subdorsal spines 4, forming a square, the dorsal 2 enlarged; spines of trunk and tail ridges blunt and moderate in size; third and seventh superior trunk spines, and fourth, eighth, and eleventh superior tail spines enlarged, with a slender, leaf-like filament; body slender, the maximum trunk depth (at seventh trunk ring) 11.2 in TL; depth of tail at third tail ring 23 in TL; trunk length 3.2 in TL; head at right angle to trunk as photographed (80° in preserved specimen); head length 6.2 in TL; snout length Fig. 2. Head of Hippocampus tyro, BPBM 35555. 2.2 in HL; eye diameter 6.25 in HL; one suborbital, 2 (Drawn by Susan Monden.) supraorbital, and 2 nose spines; coronet oval and cup- like in dorsal view, with a rugose spine to each side, 6.25 in HL; 2 supraorbital spines, angling laterally, the followed by a narrow median ridge; anterior edges of anterior twice as long as posterior, slightly longer than coronet converging to a low, arrow-like, median spine; pupil diameter; one suborbital spine, intermediate in shoulder ridge continuous middorsally, followed by length to the 2 supraorbital spines; 2 median dorsal crest-like ridge; gill opening a single middorsal slit nose spines basally on snout, the posterior twice as in neck ridge between coronet and collar of shoulder large, its length about equal to second supraorbital

Smithiana Bulletin 10: 19-21 Smithiana Bulletin 10: 19-21